Which formula can be used to describe the sequence? (see image) PLEASE EXPLAIN!

Answer:
4th formula
Step-by-step explanation:
In the sequent you have positive and negative numbers, so the formula must switch the signs. You can do that with multiplication with - (to switch sign in every next step. +*-=-, -*-=+)
So the answer is -3/4*a_n-1.
You can check the answer:
a0=64
a1=-3/4*64=-48
a2=-3/4*(-48)=36
a3=-3/4*36=-27,
So it’s right sequent 64,-48,36,-27